Polymorphism, polytypism and solid-state reactivity: The “magic” of potassium carboxylate complexes

INOR 667

Chun-Hsing Chen, fivedala@brandeis.edu, Jeremy B. Heyman, jheyman@brandeis.edu, Wen Shang, wshang@brandeis.edu, and Bruce M. Foxman, foxman1@brandeis.edu. Department of Chemistry, MS 015, Brandeis University, Waltham, MA 02454-9110
Many potassium carboxylate complexes have an unusual coordination geometry. In the solid state the complexes are two-dimensional coordination polymers, with individual potassium ions in a pseudo-five coordinate, square pyramidal environment. One of the repeat distances of the polymer is always 4 Å or 8 Å, depending on whether the carboxylates are translation related by 4 Å and superimposable, or related by 8 Å and having alternating orientations of the carboxylate. If these materials contain unsaturation, short contacts < 4 Å occur, leading to polymeric materials upon 60Co γ-irradiation. Examples include polymorphism of potassium propionate, including two polymorphs with 4 and 8 Å repeat distances, and potassium methacrylate, a 4 Å phase first shown by Morawetz to undergo solid-state polymerization. The structure of potassium methacrylate has remained a puzzle since 1962.
 

Characterization and Applications of Coordination Compounds
7:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Sci-Mix

Division of Inorganic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007